Integrated circuits (“IC's”) are ubiquitous in modern electrical products. Currently most integrated circuits are formed in individual semiconductor units called dies or dice. Each semiconductor die typically includes a silicon substrate block having multiple internal and/or external circuit layers. The circuit layers are usually formed by photolithographic or screen printing processes. The various circuits in these circuit layers may be electrically connected to a metal lead frame. The die and lead frame are often encased in a protective material such as epoxy. One or more electrical contacts provided by the lead frame are formed on or project from the surface of the die. The electrical contacts allow the circuitry in the die to be electrically connected to other electronics.
Modern electronic assemblies usually include a number of integrated circuits dies and other electronic devices that are electrically connected by a printed circuit board (PCB) or other interconnect apparatus such as ceramic multilayer interconnect boards (“MIB's”). IC dies are typically box shaped and have two oppositely positioned largest faces. The dies are usually mounted on a PCB with one of the largest faces of the die abutting a face surface of the PCB.
A process known as wire bonding is most often used to connect IC dies to a printed circuit board. With wire bond connection, connection points or bumps located on the top face of a die are soldered to thin bond wires. The other ends of the bond wires are soldered to contact pads on the PCB.
In another widely used process, solder balls are formed on contact areas on one of the large face surfaces of a die. These solder balls are then placed in contact with corresponding contact pads on a PCB. The die and PCB are then heated. Heating causes the solder balls to bond with the contact pads on the PCB thus physically and electrically connecting the die to the PCB.